Mutants of Arabidopsis

The carotenoid pathway may also be regulated by feedback inhibition from the end products. Inhibition of lycopene cyclisation in leaves of tomato causes increase in the expression of Pds and Psy-1 (Giuliano et al, 1993 Corona et al, 1996). This hypothesis is supported by other studies using carotenoid biosynthesis inhibitors where treated photosynthetic tissues accumulated higher concentrations of carotenoids than untreated tissues (reviewed by Bramley, 1993). The mechanism of this regulation is unknown. A contrary view, however, comes from studies on the phytoene-accumulating immutans mutant of Arabidopsis, where there is no feedback inhibition of phytoene desaturase gene expression (Wetzel and Rodermel, 1998). 

HARTEL, H., LOKSTEIN, H., DORMANN, P TRETHEWEY, R.N., BENNING, C., Photosynthetic light utilization and xantophyll cycle activity in the galactolipid deficient dgdl mutant of Arabidopsis thaliana, Plant Physiol. Biochem., 1998,36,407-417. 

FOCKS, N., SAGASSER, M., WEISSHAAR, B., BENNING, C, Characterization of ttl5, a novel transparent testa mutant of Arabidopsis thaliana (L.) Heynh, Planta, 1999, 208, 352-357. 

SHIRLEY, A.M., McMICHAEL, C.M., CHAPPLE, C The sng2 mutant of Arabidopsis is defective in the gene encoding the serine carboxypeptidase-like protein sinapoylglucose Choline sinapoyltransferase, Plant J., 2001, 28, 83-94. 

The results of a recent study have called this into question. The primary walls of a double mutant of Arabidopsis thaliana in which two xyloglucan xylosyltransferase genes were not expressed were found to contain no detectable xyloglucan (Cavalier et al., 2008). Compared to the wild type, the double mutant was slightly smaller and had abnormal root hairs, yet there was no catastrophic effect on cell-wall integrity as would be predicted from current cell-wall models. A possible explanation is that the pectic polysaccharide network between the... 

Heremans, B. Jacobs, M. A mutant of Arabidopsis thaliana (L.) Heynh. with modified control of aspartate kinase by threonine. Biochem. Genet., 35, 139-153 (1997)... 

Another dwarf mutant of Arabidopsis, sax], defines a step upstream of DWF1 in the brassinosteroid biosynthesis pathway [27]. Rescue experiments with intermediates showed that saxl is involved in the oxidation and isomerization of 3P-hydroxyl,A5 6 precursors to 3-oxo-A4 5 steroids (Fig. (4)). 

The elucidation of sinapoyl ester metabolism was aided by the availability of mutants. The sngl sinapoyl glucose accumulator 1) mutant of Arabidopsis had been identified based on a mutant screen for alterations in the composition of fluorescent compounds in the leaves. The screen was performed by thin layer chromatography and revealed that the leaves of the sngl mutant contained less sinapoylmalate and instead accumulated the precursor sinapoyl glucose (Lorenzen et al. 1996). 

Lorenzen, M., Racicot, V., Stack, D., Chappie, C., 1996, Sinapic acid ester metabolism in wild type and a sinapoylglucose-accumulating mutant of Arabidopsis, Plant Physiol. 112 1625-1630. 

Bharti AK, Khurana JP. 1997. Mutants of Arabidopsis as tools to understand the regulation of phenylpropanoid pathway and UV-B protection mechanisms. Phyto-chem Photobiol 65 765-776. 

Peer WA, Brown DE, Tague BW, Muday GK, Taiz L, Murphy AS. 2001. Flavonoid accumulation patterns of transparent testa mutants of Arabidopsis. Plant Physiol 126 536-548. 

Koomneef, M., Reuling, G. Karssen, C.M. (1984). The isolation and characterization of abscisic acid-insensitive mutants of Arabidopsis thaliana. Physiologia Plantarum 61, 377-83. 

Jacobs, M., Dolferus, R. Van Den Bossche (1988). Isolation and biochemical analysis of ethyl methane sulfonate induced alcohol dehydrogenase null mutants of Arabidopsis thaliana (L.) Heynth. Biochemical Genetics 26, 105-12. 

Hugly, S., McCourt, P., Browse, J., Patterson, G.W. Somerville, C. (1990). A chilling sensitive mutant of Arabidopsis with altered steryl-ester metabolism. Plant Physiology 93, 1053-62. 

Some starch-deficient mutants of Arabidopsis and Chlamydomonas have been shown to be defective in a-l,4-glucanotransferase activity. The enzyme is also known as D-enzyme. The reaction it catalyzes is as follows ... 

The precise role of polyamines in the control of dormancy and the onset of cell division in Jerusalem artichoke tubers, and for that matter in plant development per se, remains in question. Evidence from arginine decarboxylase mutants of Arabidopsis does indicate a possible role in root meristem function (Watson et al., 1998). 

Watson, M.B., Emory, K.K., Piatak, R.M., and Malmberg, R.L., Arginine decarboxylase (polyamine synthesis) mutants of Arabidopsis thaliana exhibit altered root growth, Plant J., 13, 231-239, 1998. 

GLAZEBROOK, J., AUSUBEL, F.M., Isolation of phytoalexin-deficient mutants of Arabidopsis thaliana and characterization of their interactions with bacterial pathogens, Proc. Natl. Acad. Sci., USA, 1994,91, 8955-8959. 

Reiter, W.-D. C., C. and Somerville, C. R., Mutants of arabidopsis thaliana with altered cell wall polysaccharide composition. Plant J 1997, 12 (2), 335-345. 

Vanzin, G. F., Madson, M., Carpita, N. C., Raikhel, N. V, Keegstra, K., and Reiter, W. D., The mur2 mutant of Arabidopsis thaliana lacks fucosylated xyloglucan because of a lesion in fucosyltransferase AtFUTl. Proc Natl AcadSci USA 2002, 99 (5), 3340-5. 

The dwarf mutants of Arabidopsis show, when grown in the dark, many of the characteristics of light-grown plants, including cotyledon expansion, primary leaf initiation, anthocyanin accumulation, and depression of light-regulated gene expression. Involvement of BR in de-etiolation has been discussed.816... 

Sedimentation of amyloplasts within the cell has been correlated with the capacity of the plant to perceive gravity. The buoyant mass of amyloplasts present in specialized cells in the center of the root cap and in the stem (depending on the plant species, in the endodermis, the bundle sheath, or in the parenchyma to the inside of the vascular bundle) would allow the amyloplasts to sediment inside the cell, where the cytosol would have a relatively low viscosity. This sedimentation would translate into a signal of an unknown nature, maybe through pressure onto a sensitive part of the cell or acting as a mechano transducer, etc. Whatever the nature of the signal, it eventually results in the asymmetry of the organ and its curvature. The isolation of starchless mutants of Arabidopsis thaliana and Nicotiana sylvestris has made... 

Caspar, C, Huber. S. C., and Somerville, C. 1986. Alterations in growth, photosynthesis and respiration in a starch mutant of Arabidopsis thaliana (L.), Heynh deficient in chloroplast phosphoglucomutase activity. Plant Physiol. 79, 1-7. 

Caspar. T.. and Pickard. B. G. 1989. Gravitropism in a starchless mutant of Arabidopsis implications for the starch-statolith theory of gravity sensing. Planta 177, 185-197. 

Li, L., and Preiss, J. 1992. Characterization of ADPglucose pyrophosphorylase from a starch-deficient mutant of Arabidopsis thaliana (L.). Carbohyd. Res. 227, 227-239. 

Lin, T. P., Caspar, T., Somerville, C., and Preiss, J. 1988b. Isolation and characterization of a starchless mutant of Arabidopsis thaliana L. Henyh lacking ADPglucose pyrophosphorylase activity. Plant Physiol. 86, 1131-1135. 

Hong, S.W., and Vierling, E., 2000, Mutants of Arabidopsis thaliana defective in the acquisition of tolerance to high temperature stress. Proc. Natl. Acad. Sci. U.S.A. 97(8) 4392-4397. 

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